About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

In this work, we investigate the propagation of designer surface plasmons in planar perfect electric conductor structures that are subject to a parabolic graded-index distribution. A three-dimensional, fully vectorial finite-difference time-domain method was used to engineer a structure with a parabolic effective group index by modulating the dielectric constant of the structure’s square holes. Using this structure in our simulations, the lateral confinement of propagating designer surface plasmons is demonstrated. Focusing, collimation and waveguiding of designer plasmons in the lateral direction is realized by changing the width of the source beam. Our findings contribute to applications of designer surface plasmons that require energy concentration, diffusion, guiding, and beam aperture modification within planar perfect electric conductors.

Figures (7)

(a) Principle of a gradient index based lens. A parabolic gradient (green line) of the group index (N) along the transverse direction of the propagation (Y-axis) enables the focusing or collimation of incoming beam (red arrows). A PEC structure with periodic array of square holes with varying (b) size of square holes and (c) dielectric constant, along the transverse direction of propagation (Y-axis) enables the focusing or collimation of DSPs (red arrows).

Dispersion relations calculated using Eq. 1 for a PEC structure filled with (a) different εh and fixed a= 0.85d, h=1d (b) different a and fixed εh=2, h=1d and (c) different h with fixed a= 0.85d, εh=2.

(a) Dispersion relations calculated using FDTD for a PEC structure filled with different εh. Inset shows the unit cell. (b) Variation of Ng with εh at an operating frequency of 0.3742 normalized units obtained from FDTD (dotted line) and a best fit to the data (solid line).